Device for precision feeding of flat sortation items to an input device for a sorting conveyor

ABSTRACT

The present invention is directed to transferring flat objects to be sorted towards the input device of a sorting conveyor for sorting them. This is achieved by a picking unit which periodically individualizes the flat object for sorting, places the objects on a transporting path, and a transferring unit transfers the objects to be sorted, when they come in a predetermined position on the transporting path, to an input device at a defined advancement rate. The targeted advancement rate makes it possible to place the object to be sorted in a final defined position in the input device in such a way that the subsequent treatment thereof is carried out in a reliable and automated manner. The shape and structure of the object is not important, because prior to the object reaching the predetermined transport position, the targeted displacement thereof is carried out at an pre-set advancement rate.

The invention relates to a device for precision feeding of flat sortation items to an input device for a sorting conveyor.

A device of this kind is normally used in a sorting conveyor for postal automation, such as that described, for example, in European patent application EP 827 786 A1. Said sorting conveyor generally has so-called in-feed devices which inject the flat sortation items into pockets of a continuous conveyor. From these pockets, the flat sortation items are emptied out at the physical target points assigned to them and can then be fed to their destination.

Sorting flat mail items is comparatively demanding in that the dimensions and manipulability of flat sortation items varies greatly. On the one hand, in terms of format alone there exists an almost unlimited diversity of width, height and thickness dimensions. In addition, the packaging and stiffness of flat sortation items can also vary in the extreme, ranging from hard, rigid cardboard envelopes to rather soft film-packaged brochures and magazines. Particularly problematical are the so-called mailshots which generally contain advertising material and often consist of a loose-leaved assemblage containing additional advertising inserts exceeding the dimensions of the other sheets.

Mailshots of this kind, but also other flat sortation items, are generally placed into the abovementioned feeding device in horizontally carried stacks and must be extracted individually from said stacks, which is in itself likewise a technically very demanding task. However, in order to enable these flat, generally horizontally lying sortation items to be injected into the continuous sorting conveyor using an in-feed device, it is necessary to stand said sortation items vertically. This in turn makes it necessary, however, for the sortation items to be conveyed in a very precisely pre-positioned manner to the sortation item verticalising device. This is made more difficult by the fact that especially the relatively unrigid and intrinsically inhomogeneous sortation items, e.g. the abovementioned mailshots, are particularly difficult to handle and therefore cannot generally be fed in an automated manner, but have to be manually positioned on the feeding device by an input station, which constitutes a significant cost factor.

The object of the invention is therefore to specify a device for precision feeding of flat sortation items to an input device for a sorting conveyor, thereby also enabling in particular the abovementioned particularly problematical sortation items to be fed in a sufficiently precise manner for further processing.

This object is achieved according to the invention by the device of the type mentioned above in that a take-off unit periodically singulating the flat sortation items places the flat sortation items in singulated form onto a conveying section and a feeder unit transfers the singulated sortation items with a defined forward feed to the input device after said sortation items have reached a predetermined conveying location on the conveying section.

This specific forward feed ensures that a sortation item is positioned with a defined limit position in the input device, so that further processing, in particular standing the sortation item vertically, can be accomplished reliably and in an automated manner, the format and nature of the sortation item now being irrelevant because a specific translational movement of the sortation item by precisely the forward feed takes place when the item reaches the predetermined location.

Particularly in the case of mailshots with loose-leaved inserts and the like it is particularly important that a comparatively stable edge, e.g. the folding edge, can be disposed as the underlying edge when the sortation item is subsequently stood vertically. For this purpose a particular embodiment of the invention provides that the sortation items having a preferred edge can be stacked in the take-off unit and transferred to the conveying section with the preferred edge foremost.

A particularly reliable implementation of the abovementioned feature can provide for the take-off unit to comprise a drum-like rotating unit having suction pads and a transport securing element, the suction pads acting on a sortation item nearest to the drum, and an edge, in particular a preferred edge, of the sortation item in engagement with the suction pads then being bringable into engagement with the transport securing element. This enables the suction pads to draw in the stack's bottommost sortation item close to the edge and to separate it from the overlying sortation items because of the circular path of the drum. The transport securing element controlled by the circular movement, e.g. a lever pressing the sortation item by its edge against an opposing bearing, then-grips the sortation item which is now withdrawn from the stack and conveyed to a suitable position on the circular path.

To deposit the sortation item on the conveying section it is particularly expedient for the underpressure of the suction pads to be releasable and the transport securing element to be removable from the edge. The sortation item thus lies freely conveyable on the conveying section, which, however, need not necessarily mean that the sortation item is deposited in a horizontal position, as the circular motion of the drum-like unit also permits other positions.

In a practical embodiment of the invention, the specified conveying location can be constituted by a light barrier assigned to the conveying section and/or by a contact sensor assigned to the conveying section. Additionally or alternatively, the specified conveying location can be constituted at the same time or alternatively by the end of the conveying section.

A feeder unit that is mechanically particularly reliable to operate and easy to construct is produced if said feeder unit comprises a telescopic unit with a traversable slide, said slide moving out when the sortation item reaches the specified conveying location, and the defined forward feed corresponding to the predetermined outward travel. The moving out and also the subsequent retraction can be activated electromotively, but also pneumatically, for example. Depending on how these activation elements are controlled, the withdrawal path can be varied within appropriate limits, so that the withdrawal path can be definitely shorter than the length of the withdrawal means provided, e.g. a withdrawing bar.

In order to be able to ensure that the defined point for the transfer of the sortation item to the input device is always maintained even during continuous automated operation, the slide of the telescopic unit is adjusted in such a way that it has returned to its normal position before the sortation item following the sortation item just ejected reaches the specified conveying location. Note here that it is perfectly possible for the next sortation item to be already being transported to the predetermined conveying location over the returning slide. It is important solely that the slide shall have returned to its normal position at least by the time the sortation item has reached the predetermined conveying point and is therefore about to be transferred onto the slide.

In a particularly advantageous embodiment of the telescopic unit, the slide of said telescopic unit can have a continuous conveying belt which is not driven as the slide moves out and which is driven as the slide is retracted. This makes it possible for the position of the sortation item to remain unchanged relative to the slide as the latter moves out and for the deposition/transfer of the sortation item onto/to the input device to be appropriately assisted by a suitable conveying belt drive.

Particularly critical for the deposition/transfer of the sortation item by the slide onto/to the input device is the backward directed retraction travel of the slide. This backward directed movement is equalized relative to the sortation item if a driving element for the slide's conveying belt is linked to the motion of the slide, a free wheel being provided for the outward travel and, for the retraction travel, the speed of the conveying belt being largely matched to the speed of said retracting motion, but being of opposite sign.

Another particularly advantageous and easily constructed variant for the telescopic unit is provided by a telescopic unit comprising at least one system of two roller pairs coupled via a closed belt and having the following characteristics:

-   -   a) the position of the two rollers relative to one another         within a roller player is fixed;     -   b) one roller pair is stationary and the other roller pair is         mounted on the traversable slide, which performs the outward         travel/inward travel;     -   c) each roller pair comprises at least one roller equipped with         a free wheel so that     -   c1) as the slide moves out, the belt only rolls via the rollers         of the stationary roller pair, and     -   c2) as the slide retracts, the belt only rolls via the         slide-mounted rollers.

This means that further separate drive elements for driving the belt are not even required on the slide because, as the slide retracts, the belt rolls in the conveying direction via the two rollers of the slide corresponding to the backward movement and the sortation item thus does not detect that the slide is being removed from under it. It therefore remains exactly in the limit position of the outward travel of the slide, precisely as intended. Thanks to the free wheels provided for each roller pair, the belt remains unchanged in the region of the slide as the latter is moved out, because during the outward travel the belt rolls via the rollers of the fixed roller pair, and the slide-mounted rollers do not allow the belt to roll via these rollers because of the now locking free wheel.

In order to be able to facilitate the transfer of the sortation item from the conveying section onto the slide, the conveying section, at least in the region of the limit position of the slide of the telescopic unit, and the slide itself can both comprise strip-shaped spaced conveying belts, the strip-shaped conveying belts of the conveying section and of the telescopic section being disposed alternately. This produces so to speak a kind of transfer zone which is at the same time the (final) component of the conveying section and of the slide.

In order that in particular the speed can also be selected comparatively high, it is possible, as mentioned above, for sortation items to be conveyed to the aforesaid transfer zone even while the slide is still travelling back. In order to ensure that the effect of the returning slide on the sortation items being conveyed in the opposite direction is negligible, the level of the slide's strip-shaped belts used to carry the sortation item can be disposed slightly lower than the level of the strip-shaped belts of the conveying section at which the sortation item has been conveyed thereto. Only when the slide has moved out and the sortation item has been transported forward over the end of the conveying section does the slide then receive the sortation item in a sliding manner. This operation can be significantly assisted by providing the belt or belts of the slide with an adhesive surface. In addition or alternatively, the sortation items can also be suitable held—although not necessarily fixed in the strict sense—on the slide. For this purpose the sortation items, until they reach the predetermined conveying location, can be brought into contact with a roller bearing mounted spring element which (gently) presses the sortation item against the belt or belts of the slide.

Another feature assisting the transfer from the conveying section to the slide can be achieved if the slide of the telescopic unit is adjusted in such a way that, when the sortation item is transferred from the conveying section to the slide, said slide has at least approximately the same speed as the sortation item being transported on the conveying section. This means that there is no difference in the relative speeds during transfer of the sortation item from the conveying section to the slide, thereby ensuring that there is no unwanted shifting of the sortation item on the slide. Such shifting might otherwise occur, for example, when the slide accelerates from the normal position with a sortation item already lying thereon.

The object can be achieved using a solution quite different from the solutions explained above if the feeding unit is implemented with a disk-like, rotating, non-rotationally-symmetrical conveying element which acts with its axially outer areas on the sortation items which have reached the specified conveying location and thus initiates forward feeding to the input device until the axially inner areas lose contact with the sortation item. In this way the sortation items are pulled along by the conveying element as long as the axially outer areas are in engagement with the sortation item, so that a defined forward feed is also achievable in this manner. Depending on the thickness of the sortation item, a height adjustment can be provided for the conveying element, with the result that sortation items of different thickness can nevertheless remain in engagement with the conveying element for the same length of time. Similarly, there can likewise also be provided a wobble plate which, because of its unbalance, is likewise only ever in engagement with the sortation item for a certain time per revolution, thereby ensuring a defined forward feed of the sortation item.

Further advantageous embodiments of the invention are set forth in the other sub-claims.

Exemplary embodiments of the invention will now be explained in further detail with reference to the accompanying drawings in which:

FIG. 1 shows a schematic plan view of a first positioning device with downstream input device;

FIG. 2 shows a schematic side view of the first positioning device;

FIG. 3 shows a schematic plan view of a second positioning device with downstream input device;

FIG. 4 shows a schematic side view of the second positioning device;

FIG. 5 shows a schematic plan view of a third positioning device;

FIG. 6 shows a schematic side view of the third positioning device;

FIG. 7 shows a schematic side view of a telescopic unit in the moved-out state; and

FIG. 8 shows a schematic side view of the telescopic unit according to FIG. 7 in the retracted state.

FIG. 1 shows a schematic plan view of the first positioning device 2 with which flat sortation items 6 in a horizontal stack 4 are transferred in a positionally precise manner to a partly illustrated input device 8. Precision feeding is so critically important because the sortation items 6 are then rotated from horizontal to vertical in the part of the input device 8 shown here and then injected using an in-feed device not shown here into pockets of a sorting conveyor likewise not depicted in further detail here. As the above-mentioned process steps for sorting the sortation items 6 take place at a comparatively high sorting speed, it is therefore clear that the sortation items 6 must be very precisely manipulable at all times.

The operation of the first positioning device 2 will now be described with reference to FIGS. 1 and 2, said operation essentially also applying to a second positioning device 10 shown in more detail in FIGS. 3 and 4, and to a third positioning device 12 described in more detail in FIGS. 5 and 6.

In the exemplary embodiment, the flat sortation items 6 are advertising leaflets folded in DIN A4 format into which one or more loose sheets are inserted. The leaflets are not stapled together, but only intercalated as a loose-leaved assemblage. It is obvious that such sortation items 6 are extremely difficult to handle because, apart from the folded edge hereinafter referred to as the preferred edge 14, they provide no points of contact for positionally precise automated conveying.

These sortation items 6 are now deposited in the stack 4 on a tray 18 above a singulation drum 16, said singulation drum forming part of a take-off unit 15 shown offset in enlarged form inside the dashed lines in FIG. 2 for the sake of clarity. The bottommost sortation item 6a is then actively sucked in from below by means of suction pads 20 disposed on the rotating singulation drum 16 and thus initially deflected downward out of the stack 4. By means of a lever 22, the sucked-in sortation item 6 a is simultaneously pressed by its preferred edge 14 against an opposing bearing 24 disposed on the singulation drum 16 so that the sortation item 6 a sucked-in and clamped by the lever 22 now follows the circular motion of the singulation drum 16. After a 180° rotation, the underpressure in the suction pads 20 is released and the lever 22 is swung away from the opposing bearing 24 so that the thus singulated sortation item 6 a is now transferred to a conveying section 26 which conveys the singulated sortation item 6 a to a telescopic unit 30 by means of strip-shaped conveying belts 28.

The telescopic unit 30 will be described in detail below in connection with FIGS. 7 and 8. Suffice it to say at this juncture that a traversable slide 32 of the telescopic unit 30 moves out at the speed of the strip-shaped belts 28′ of the conveying section 26 that are disposed as the last element in said conveying section 26, i.e. therefore performs an outward travel when the preferred edge 14 of the sortation item 6 a reaches a light barrier 34. As it does so, the slide 32, which likewise has strip-shaped belt systems 38, covers a defined forward feeding distance and, as it retracts, i.e. performs the backward directed inward travel, deposits the sortation item 6 a on a conveying belt 36 in the input device 8 from where it is then conveyed in the direction perpendicular to the previous conveying direction in the input device 8 and rotated to the vertical position, there being additionally provided a roller element 42 which is pressed against the conveying belt 36 whenever the sortation item 6 a has just been deposited, which helps to ensure that the sortation item 6 a continues to maintain the precise deposition location.

In order to be able to deposit the sortation item 6 a in a positionally precise manner on the conveying belt 6, i.e. specifically so that the preferred edge 14 always come to be at the same place, the inward travel is designed in such a way that the backward directed motion of the slide 32 is equalized by having the conveying belt systems 38 roll across the slide's leading edge 40 adjacent to the sortation item's preferred edge 14. A distinctive feature of the invention is therefore that the position of the preferred edge 14 relative to the leading edge 40 of the slide 32 remains unchanged during the outward travel and the leading edge 40 withdraws relative to the preferred edge 14 during the inward travel, which, however, is equalized relatively speaking for the sortation item 6 a by the conveying belt system 38 rolling across the leading edge 40. This means that the sortation item 6 a is maintained in a precise position even when the slide is retracting, which is of major importance for the further conveying of the sortation item 6 a and an essential design objective for the positioning device 2.

As FIGS. 3 and 4 clearly show, the second positioning device is only slightly modified compared to the first positioning device 2, basically only the path of the conveying section 26 having been changed. For space-saving reasons in terms of width, the available height is utilized and the sortation items 6 a singulated using the singulation drum 16 are first conveyed vertically for a distance, then horizontally and finally obliquely downward to the telescopic unit 30. However, there is once again provided a light barrier (not shown in further detail here), the reaching of which by a sortation item 6 a causes the slide 32 to move out. In addition to the previously shown components of the telescopic unit 30, there is now also shown a pneumatic unit 44 driving a ram 46 linked to the slide 32. The pneumatic unit 44 could also be replaced by an electromotive drive for the ram 46 which could also allow quieter operation under suitable circumstances. For the second positioning device 10, as in the case of the preceding variant, the telescopic unit 30 is again shown in the moved-out position.

As FIGS. 5 and 6 clearly illustrate, the third positioning device 12 is only slightly modified compared to the first and second positioning devices 2 and 10 respectively, the sortation item 6 a here being transferred in a vertically falling direction onto the slide 32 of the telescopic unit 30. This variant thereby enables the input device 8 to be simplified so as to render obsolete the conveying section for rotating the sortation item 6 a from the horizontal to the vertical position. However, in terms of guidance and of accomplishing the forward feed by means of the outward travel of the slide 32, this variant is essentially unchanged with respect to the two preceding variants.

A particularly preferred variant for the telescopic unit 30 is schematically illustrated in FIGS. 7 and 8. According to this embodiment, the telescopic unit 30 comprises a plurality of conveying belt systems 38 each representing a conveying belt strip. The mode of operation will now be explained with reference to one of said conveying belt systems 38. Each conveying belt system 38 has two roller pairs 48, 50 linked by a closed belt 38′ and comprising the two rollers 48 a and 48 b and 50 a and 50 b respectively, the position of the two rollers 48 a and 48 b and 50 a and 50 b respectively being fixed relative to one another within a roller pair 48, 50. The roller pair 48 is disposed in a stationary manner on the telescopic unit 30 and the other roller pair 50 is mounted on the slide 32 which performs the outward travel in the direction of an arrow 52 and the inward travel in the direction of an arrow 54.

In the example, the rollers 48 b and 50 b each have a free wheel, the roller 48 b being locked against movement in the counter-clockwise direction and the roller 50 b against movement in the clockwise direction. As a result, when the slide 32 moves out, the belt 38′ only rolls via the rollers 48 a and 48 b of the stationary roller pair 48, the rollers 48 a and 48 b rolling clockwise. This means that, once it has reached the light barrier 34, the sortation item 6 a no longer changes its position relative to the roller 50 a during the outward travel, which is absolutely as intended. Conversely and again as required, during the inward travel the belt 38′ only rolls via the rollers 50 a and 50 b mounted on the slide 32, the roller 50 a running clockwise and the roller 50 b counter-clockwise. The sortation item 6 a does not therefore “feel” the inward travel at all, but maintains its limit position attained with the outward travel, as required. The preferred edge 14 of the sortation item 6 a therefore always comes to be at precisely the required position on the input device 8. To assist this operation, there is provided in each case a spring plate 58 mounted on rollers 56 which gently presses the sortation item 6 a against the adhesively implemented conveying belt 38′ during the outward travel and which rolls back over the sortation item 6 a—frictionlessly with the sortation item 6 a—during the inward travel.

It is also very clearly illustrated that the conveying belt 38′ is disposed slightly below the conveying belt 28′ which can still be regarded as being part of the conveying section 26, so that, even when the slide 32 is retracting, a new sortation item 6 a can already be being conveyed above it to the light barrier 34. This area can therefore be regarded as a kind of transfer zone 26 for transfer from the conveying section 26 to the telescopic unit 30.

Reference List

-   2 first positioning device -   4 stack -   6 flat sortation items -   6 a singulated flat sortation items -   8 input device -   10 second positioning device -   12 third positioning device -   14 preferred edge -   15 take-off unit -   16 singulation drum -   18 tray -   20 suction pads -   22 lever -   24 opposing bearing -   26 conveying section -   28 strip-shaped conveying belts of the conveying section -   28′ conveying belts disposed last in the conveying section -   30 telescopic unit -   32 slide -   34 light barrier -   36 conveying belt -   38 conveying belt system -   38′ belt -   40 leading edge of slide 32 -   42 roller element -   44 pneumatic unit -   46 ram -   48,50 roller pair -   48 a, 48 b rollers of roller pair 48 -   50 a, 50 b rollers of roller pair 50 -   52, 54 arrow indicating inward/outward travel direction (slide) -   56 rollers -   58 spring plate 

1. a device for precision feeding of flat sortation items to an input device of a sorting conveyor, comprising: a take-off unit arranged to periodically singulate the flat sortation items and places the flat sortation items in singulated form onto a conveying section; and a feeder unit arranged to transfers the singulated sortation items, with a defined forward feed, to the input device after the sortation items have reached a predetermined conveying location on the conveying sections.
 2. The device according to claim 1, wherein the sortation items comprise a preferred edge and the device further comprises means for stacking the sortation items in the take-off unit and transferring the sortation items to the conveying section with the preferred edge at a foremost location.
 3. The device according to claim 1, wherein the take-off unit comprises a drum-like rotating unit having suction pads and a transport securing element, the suction pads arranged to act on a sortation item nearest to the drum such that, an edge, of the sortation item in engagement with the suction pads may be brought into engagement with the transport securing element.
 4. The device according to claim 3, wherein the suction pads include releaseable vacuum means which when released effect the transport securing element to be removed from the edge, the vacuum being releasable after a specifiable angular rotation distance.
 5. The device according to claim 1, wherein the specified conveying location includes a light barrier assigned to the conveying section and/or a contact sensor assigned to the conveying section.
 6. The device according to claim 1 wherein the specified conveying location is represented by an end of the conveying section.
 7. The device according to one of claim 1, wherein the feeder unit comprises a telescopic unit with a traversable slide, the slide arranged so as to move out when the sortation item reaches the specified conveying locations and a defined forward feed corresponding to a predetermined outward travel.
 8. The device according to claim 7, wherein the slide of the telescopic unit is adjustable so that it can return to its normal position before the sortation item following the sortation items which were just ejected reaching the specified conveying location.
 9. The device according to claim 7, wherein the slide of the telescopic unit has a continuous conveying belt which is not driven as the slide moves out and is driven as the slide retracts.
 10. The device according to claim 9, further comprising a driving element for a conveying belt of the slide, the driving element being linked to the slide's motion and comprising a free wheel arranged to provide for the belt's outward travel and, speed control means arranged for the inward travel so that the speed of the conveying belt is at least largely matched to the absolute speed of the inward travel, but in an opposite direction.
 11. The device according to claim 7, wherein the telescopic unit comprises at least one system of two roller pairs linked via a closed belt, wherein: a) the position of the two rollers within a roller pair is fixed relative to one another; b) one roller pair is stationary and the other roller pair is mounted on the slide performing outward and inward travel; c) each roller pair comprises at least one roller equipped with a free wheel, so that c1) as the slide travels out the belt only rolls via rollers of the stationary roller pair, and c2) as the slide retracts the belt only rolls via rollers mounted on the slide.
 12. The device according to claim 7, wherein both the conveying section at least in the region of the normal position of the slide of the telescopic unit and the slide comprise strip-shaped spaced conveying belts, the strip-shaped conveying belts of the conveying section and of the telescopic unit being alternately disposed.
 13. The device according to claim 12, wherein a level of the strip-shaped belts of the slide may be used as support for the sortation item, the level being disposed slightly lower than a level of the strip-shaped belts of the conveying section in which the sortation item has been conveyed.
 14. The device according to claim 7 wherein the at least one of the belt and belts of the slide comprise an adhesive surface.
 15. The device according to claim 7, further comprising a roller-bearing-mounted spring element arranged such that until they reach a predetermined conveying location, the sortation items (6 a) can be brought into engagement with the roller-bearing-mounted spring element which presses the sortation items against at least one of the belt or belts of the slide.
 16. The device according to claim 7, wherein the slide of the telescopic unit is adjustable such that the slide has at least approximately a speed of the sortation item transported on the conveying section when the sortation item is transferred from the conveying section to the slide.
 17. The device according to claim 1 wherein the feeder unit comprises a disk-like, rotating, non-rotationally-symmetrical conveying element arranged to act with its axially outer areas on the sortation items which have reached a specified conveying location and thus initiates forward feeding to the input device until the element's axially inner areas lose contact with the sortation item.
 18. The device according to claim 3, wherein the edge of the sortation item is a preferred edge. 